Spark-plug



M. P. SULLIVAN.

SPARK PLUG.-

APPLICATION FILED MAR. I8, 1918.

1,373,682. Patented Apr. 5, 1921.

IN VE N TOR IWHZJR/CE F EL/LL/VHN A TI'ORNE Y UNITED STATES.

FATENT" UFHCE.

MAURICE PPSI Y LLIVAN, OF TORRINGTON, CONNECTICUT, ASSIGNOR TO SPLITDORF ELECTRICAL COMPANY, OF NEWARK, NEW JERSEY.

SPARK-PLUG.

To all whom it may concern:

Be it known that I, MAURICE P. SULLIVAN, a citizen of the United States, residing at Torrington, in the county of Litchfield and State of Connecticut, have invented certaln new and useful Improvements in Sparktion. v

This invention relates to spark plugs and comprises means whereby high tension electric current, generated I by any suitable method, is caused toproduce, in a highly efficient and desirable manner, ignition sparks for the purpose of firing the explosive charge in the cylinders of an internal combustion engine. 1 It has been found that the ordinary or Plugs, .of which the following is a specificausual type of spark plug is far from satisfactory when used in aeroplane engines on account of the dutles imposed upon it by an engine of thiskindg In the case of an internal combustion engine used on an automobile the engine speed is continually varying, due to the varyingload, and at only short intervals of time is the full horse power of the engine required and the maximum horse power developed is "not very large, while in an aeroplane engine the horse power developed is a number of times larger than in an automobile engine and this horse power is'being developed substantially at a constant rate for a number of hours, hence it will be readily understood that the duties imposed upon the spark plugs used in an will be easy and aeroplane engine are exceedingly severe and special plugs have had to be designed to meet this new and unusual condition. It is, therefore, the object of this invention to produce a plug which will operate satis factorily in an aeroplane engine by protecting andventilating the-insulating member or members to prevent their destruction by the severe heating and influence of the explodinggases:

Another object of my. invention is to pro vide a plug which is comparatively simple in 'itsjconstruction and therefore one that relatively cheap to manufacture; j 'v 3 7 These andother objects will'be apparent after a studyof'the further description together with the accompanying drawing a which forms a part of the specification.

'In-the drawing, Figure 1 illustrates a view Specification of Eetters Patent.

Patented Apr. 5, 1921.

Application filed March 18, 1918. Serial No. 223,213.

- different views, 1 is a shell having threads 2 cut thereon for the purpose of screwing the shell and complete plug into the engine cylinder by means of a wrench applied to the hex portion 26. In some cases the shell 1 may have a'groove 3 cut therein for the purpose of lightening the shell and increasing the heat radiating surface. The upper part of the shell 1 has a chamber' l therein, and opening outwardly from this chamber are a number of holes 5 for the purpose of ventilation, Leading from the chamber 4; toward the threaded end of the shell is a hole 6, tapering upward. A central electrode 7 has wound around it micainsulation 8. The application of mica 8 to the central electrode 7 is such that the mica tapers upward. Mounted on the mica 8 is a gland 9 which is tapered inside to fit the mica 8 and is ground to a taper on the outside to fit the tapering hole 6. After the mica 8 and gland 9 have been assembled to the central electrode 7, the upper end of which is threaded at 10, the lower end is turned off to the proper length and an electrode terminal 11 is fastened to the electrode 7 by staking thesame over at 12. The electrode terminal 11 is preferably made of good heat conducting material, such as copper, whereby the heat generated in the internal combustion chamber will be conveyed to the central electrode 7 and carried upward and dissipated through the holes 5 and through further means which will. be later described. I prefer to make the electrode 7 tapering, as indicated at 13, in order to leave as much of a chamber as pos sible between its inner edge and the lower end of the gland 9, furthermore, so that a sharp edge 14. will be presented toward the shell 1 for the purpose of furnishing a spark gap. After the central electrode unit is put up, as in the form shown in Fig. 2, it is then slipped into the'shell 1 and a-spacing collar 15 is then applied to the upper portion of the shell. An insulator 16, preferably of porcelain, is theniput on over the central electrode 7 and the mica insulation 8 with its lower flange 17 resting upon the collar 15. The insulator 16 has a bore 18 large enough to leave a clearance space between the central electrode structure and its inner walls. An air space 19 is also provided around the lower exterior or skirt portion of the insulator 16 and the spacing collar 15, which latter part may have a series of holes similar to holes in the shell 1; but by way of distinction I stamp these holes in the form of letters to indicate the manufacturers name, two of such letters of the word Splitdorf being indicated. The insulator 16 may have grooves 20 therein for the pun pose of giving greater radiating surface. Lockwasher 21 and cap nut 22 which engage the threads 10 on the central electrode '7 are used to draw the parts together and lock them inoperative position. The nut 22 may have a round end 23 for the reception of a certain type of cable terminal or it may have a screw 24 to take another type of cable terminal. From the above it will be seen that by the use of a properly proportioned and ground taper fit between the shell 1 and the gland 9, I am enabled to secure a perfect gastight joint. The gland 9 also serves to hold the mica from expanding and from the means employed a large heat radiating surface is provided.

Inthe modified form shown in Fig. 3, tl e shell 1 and the gland 9 are not made with a. long taper as shown in Figs. 1 and 2 but more abrupt taper 25 is used in the manner indicated. The rest of the central electrode is the same as that shown in Fig. 2. The insulator 16 is of somewhat different shape from that shown in Fig. 1 otherwise the parts of the plug shown in Fig. 3 are the same as heretofore described.

It will be understood that the term of shell or insulator or other parts may be varied considerably without departing from the. spirit of my invention or the scope of the appended claims.

Having thus described my invention what I claim is 1. In a spark plug, the combination of a shell having threads cut at one end thereot for the purpose of screwing said shell into an engine cylinder, a chamber at the opposite end and a. bore tapering upward from the threaded end into said chamber, a unitary structure consisting of a central electrode with only wound mica insulation thereon, a tapered metallic gland securely positioned on the wound mica and a terminal attached to the end of said central electrode, a fixed distance from said gland. said unitary structure being adapted to fit within said shell in such a manner that the taper on said gland engages the tapered bore on said shell so as to give a predetermined spark gap between the terminal and the shell, a spacing collar resting on the upper part of said shell, an insulator fitting over the central electrode and resting on said collar and a nut adapted to screw on to the upper part o'l 'the central electrode to draw all of said parts securely into operative position. as described.

2. In a spark plug, the combination of a shell having one end threaded for the purpose et screwing said shell into an engine cylinder, and having a tapered bore extending upward from the threaded end of said shell, a metallic gland having a tapering surface adapted to fit said bore, a central electrode extending through said gland and shell but insulated entirely therefrom by mica securely wrapped around said electrode and tightly fitting within the bore of said gland, said central electrode carrying a circular sparking block of good heat conducting material a definitely fixed distance from the gland, a spacing collar mounted on said shell, an insulator supported on said spacing collar and means for drawing the central electrode upward to cause said gland to engage said shell and to hold the said insulator and spacing collar in working position as described.

3. In a spark plug, the combination of a shell having threads cut at one end thereof for the purpose of screwing said shell into an engine cylinder, afchamber at the opposite end and a bore tapering upward from the threaded end into said chamber, a unitary structure consisting of a central electrode having only wound mica insu1ation thereon so as to taper upwardly, a metallic gland bored to fit the taper of said mica insulation and ground on its exterior surface to fit the tapered bore in said shell and a block tapering to a knife edge attached to the end of said electrode but definitely spaced away from said gland, said unitary structure being adapted to fit within said shell in the manner described, a spacing collar adapted to rest on the top part of said shell and inclosing the opening of said chamber, an insulator supported on said c011 lar and having a skirt extending downward around the upper portion of the mica on said central electrode and spaced apart from the wall of said collar thereby forming an air space, ventilating holes through said collar and in said shell extending into said chamber. and means engaging the upper partof said central electrode for holding all of said parts securely in operative position.

4. In a spark plug, the combination of a shell having threads cut atone end thereof for the purpose of screwing said shell into an engine cylinder, a chamber at the o posite end having perforated walls and a ore extending from the threaded end upwardly into said chamber, a central electrode positioned within said bore by means of a cone shaped mica wrapping carrying a metallic 130 gland having a bore adapted to fit said mica cone, said gland Having its outer surface tapered to fit a corresponding taper on said bore, said electrode carrying at its lower end 5 a block spaced longitudinally a fixed distance from said gland and terminating in a knife edge adjacent the interior Wall of said shell and tapering upwardly to form a gas space around the lower portion of said mica 10 Wrapping, a porcelain insulator supported on the upper part of said shell and having a skirt extending downwardly around the uppe part of said mica cone, With means for clamping the porcelain insulator in place on the shell, said means serving also to hold the central electrode in Working position within said shell.

In Witness whereof, I aflix my signature.

MAURICE P. SULLIVAN. 

